1. Field of the Invention
The present application relates to an optical film, a circular polarizing plate and a display device.
2. Discussion of Related Art
A retardation film may be used in various fields. The retardation films may be on one or both sides of a liquid crystal cell for improving the viewing angle of a liquid crystal display (LCD). In Japanese Patent Publication No. 1996-321381, retardation films are used to prevent reflection and ensure visibility of a reflective LCD or an organic light emitting device (OLED).
As retardation films, there are ½ or ¼ wavelength retardation film according to its phase retardation property. However, the phase retardation property of a conventional ½ or ¼ wavelength retardation film is changed depending on wavelength. Therefore, there is a problem that ranges, within which retardation films function as the ½ or ¼ wavelength retardation film, are restricted to limited ranges. For example, films functioning as the ¼ wavelength retardation films with respect to light having the wavelength of 550 nm don't frequently function as the ¼ wavelength retardation films with respect to light having the wavelength of 450 or 650 nm.